Paper appearing at the output of a paper machine has a relatively rough surface and usually requires further processing to level and compress the surface. Additional processing is generally accomplished by calenders and super calenders. Calenders are a set pair of hard metal rolls which level the peripheral surfaces of the paper so that parts of the paper forming the outer surface lie essentially in one plane. Super calenders are a pair of rolls wherein one of the pair is a hard metal roll which is paired with an elastically yielding roll. The elastic roll is super calenders is usually in the form of a great number of paper sheets fitted on a shaft and compressed in an axial direction of the shaft. Super calenders compress the paper web and close pores in the web's outer surface so as to smooth an add luster to the paper.
A principal requirement for the elastic roll for a super calender or embosser is a degree of resilience. A simple test for indicating the resilience of an elastic super calender roll is to indent a pair of rolls by passing a sheet of cardboard through the nip and then measuring the mark of indentation after successive conditioning cycles. It would be highly desirable to provide an elastic roll that can heal rapidly from any sign of the indentation. The rolls of this invention were completely healed after only three conditioning cycles. A conditioning cycle involves running the roll at a speed of 152 m/minute (500 ft minute) and at a linear pressure of 350 KN/m (2000 pli). 90 ml (3 oz.) of water is applied to the ingoing nip and the roll is allowed to run for a period of 5 minutes. The roll is then stopped for inspection and analysis.
U.S. Pat. No. 3,707,752 to Brafford et al. discloses a roll which is manufactured by winding a continuous strip of a mat of acrylic fibers, polyester fibers or mixtures of these fibers which have been saturated with epoxy resin. A plurality of layers of the mat are built up onto the roll.
U.S. Pat. No. 4,669,163 to Lux et al. is directed to a fiber roll manufactured by stacking a plurality of polyolefin segments into a pile and compacting the pile while restraining the pile in its compacted configuration.
U.S. Pat. No. 2,801,461 to Kusters discloses a roll made of a plurality of flat, angular, axially compressed disks mounted and restrained under compression on a support shaft. The disks are composed of nonwoven fibers bonded with vulcanized latexes. The fibers include tensilized nylon and natural fibers such as ramie, cotton, sisal-hemp.
U.S. Pat. No. 3,853,677 to Kai discloses a fiber roll made from axially compressed disks of a nonwoven fabric formed from a mixture of cotton or wool fibers and a mixture of fiber yarns such as polyester, nylon and rayon wherein the fibers are bonded with a resinous material. The fiber roll has a high Poisson's ratio.